Sustainable local energy sources call for energy supply systems having their local power grids supplied by electrical power sources, which are independent of the main grid provided by the local or regional electricity supplier. The electrical power source may be a renewable energy device, such as a solar cell module or a wind turbine. Or it may be an electrical storage device, such as a battery, in which case the energy supply systems can be run with backup when the main grid is experiencing a power outage.
In either case, the local power grid or microgrid is supposed to function as a self-sufficient and reliable electricity provider for one or multiple loads connected to it. The electrical power source is usually connected to an inverter device, which transforms the usually DC power of the electrical power source to an AC power to feed into the local power grid. In such a microgrid environment, controlling one or multiple of the loads may be desirable in order to guarantee reliable operation of the system even when the electrical power source is experiencing fluctuations or is running low. As part of a load management process, certain non-essential loads may be disconnected or run at a lower power level in order to ensure power delivery to indispensable or essential loads. Furthermore, such control capabilities may be exploited for implementing remote control for home automation.
Systems for controlling power to a load can be implemented with an intelligent or controllable power outlet or power receptacle, which the load is plugged into. Such solutions usually require one operator or source of a control signal for controlling the load and a medium or channel to carry the control signal. The command is typically sent in the form of radio signals, such as wifi, zigbee, z-wave, or logic signals in a separate communications bus, such as Modbus, canbus, etc. There are other approaches that use embedded communication protocols in the power lines, such as Broaband over the Power-line or BPL. All of these implementations allow the transmission of complex signals that need to be decoded and acted upon by the recipient.
These solutions can be extremely complex and therefor result in very expensive propositions, leading to costs per receptacle, which are multiple times that of a normal “dumb” receptacle. Furthermore, the use of such systems is not always reliable, as they are extremely susceptible to the environment they are exposed to. In the case of BPL, circuit connections and distances can significantly attenuate the transmission line, making it very difficult to maintain constant communication. Wi-Fi and other means can have difficulty achieving proper range if there are walls and objects in direct line of sight between two of the nodes.
Therefore, there is a need for a more simple approach for controlling power to a load that can render a more reliable response for certain applications. It is therefore an object of this invention to provide an energy supply system and an electrical outlet for controlling the power supplied to one or multiple loads in a reliable and economical fashion.